Vol. 53 - Alaska Resources Library and Information Services

outer shelf during those years.
Samples in June 1979 (NOAA) confirmed
this trend when the highest monthly mean density of 1798+926 P. tridens
larvae/100 m 2 occurred in June 1979 in stratum 3.
A cross-shelf comparison of P. tridens larvae incorporating 1978
PROBES data appears in Table 6.6. Unlike the homogeneous distribution
of P. borealis larvae throughout the St. George Basin between the
100-200 m isobaths (Table 6.5; strata 8, 2, and 5), P. tridens larval
distribution was much more concentrated near the Aleutian Peninsula
(stratum 5) in the outer shelf domain just north of Unimak Pass.
Generally
higher larval densities seaward of the shelf break showed that to
be the area of greatest abundance with the maximum density appearing
closest to the coastal area in stratum 4 (although this last density was
calculated from only 2 stations).
P. tridens larvae were less abundant
in the outer shelf domain and virtually absent (except for 1 of 36
stations) from the middle shelf domain.
P. tridens larvae were not caught in sufficient abundance to
analyze the vertical depth distribution in 1980, but MOCNESS data from
PROBES 1981 (Fig. 6.16) revealed a homogeneous depth distribtion of P.
tridens larvae in the top 60 m, similar to P. borealis larval vertical
distribution (Fig. 6.11).
The total cumulative percentages of larvae in
each of the depth intervals were 31% in the uper 20 m, 54% in the upper
40m, 83% in the upper 60 m and 97% in the upper 80 m. A breakdown of
the data gave similar results for both 100-200 m stations and 200-1800 m
stations.
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